U.S. patent number 4,868,549 [Application Number 07/050,806] was granted by the patent office on 1989-09-19 for feedback mouse.
This patent grant is currently assigned to International Business Machines Corporation. Invention is credited to Frank J. Affinito, John F. Beetem.
United States Patent |
4,868,549 |
Affinito , et al. |
September 19, 1989 |
Feedback mouse
Abstract
A mouse for use in a video display system for controlling cursor
movement on a display screen provided with feedback means which
produces resistance to the motion of the mouse as the cursor moves
across predetermined areas of the display screen. In its most
straight forward realization it comprises an electromagnet and
control circuit which operates independently of the pickup and
location sensing control of the mouse to produce a magnetic field
which acts cooperatively with a substantially planar magnetic
surface to produce a resistance to the motion of the mouse when
energized.
Inventors: |
Affinito; Frank J. (Ridgefield,
CT), Beetem; John F. (Madison, WI) |
Assignee: |
International Business Machines
Corporation (Armonk, NY)
|
Family
ID: |
21967548 |
Appl.
No.: |
07/050,806 |
Filed: |
May 18, 1987 |
Current U.S.
Class: |
345/164 |
Current CPC
Class: |
G06F
3/016 (20130101); G06F 3/03543 (20130101); H01H
2003/008 (20130101) |
Current International
Class: |
G06F
3/033 (20060101); G06F 3/00 (20060101); G06F
003/03 (); G06K 011/06 () |
Field of
Search: |
;340/707,709,710,706,407
;178/18 ;273/D28,148B ;74/471R,471XY ;901/10 ;188/161,163
;303/20 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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119437 |
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Jul 1984 |
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JP |
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0081631 |
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May 1985 |
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JP |
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116026 |
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Jun 1985 |
|
JP |
|
0179821 |
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Sep 1985 |
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JP |
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Other References
IBM Technical Disclosure Bulletin, vol. 27, No. 10B, Mar. 1985, p.
6299, "Mouse/Keyboard Concept Incorporating Unique Devices for
Controlling CRT Display Cursors". .
"New Role for `Mice`" by J. Timothy Ohsann, Research Magazine,
spring 1987, p. 22, IBM Corp., Thomas J. Watson Research Center,
Yorktown Heights, N.Y. 10598. .
IBM Technical Disclosure Bulletin, vol. 28, No. 3, Aug. 1985, p.
1343, "Seeing Eye Mouse" by L. Comerford..
|
Primary Examiner: Oberley; Alvin
Attorney, Agent or Firm: Schlemmer; Roy R.
Claims
Having thus described our invention, what we claim as new, and
desire to secure by Letters Patent is:
1. In the combination of a display system including a display
screen, a video display controller and an input mouse including
means cooperable with the display controller for moving a cursor on
the display screen in response to motion of the mouse, the
improvement which comprises a resistive feedback system detectable
by the user of the mouse including:
electromagnetic means for producing an operator-discernible
resistance to the motion of the mouse, as the cursor on the screen,
whose motion is controlled by said mouse, moves across
predetermined locations on the screen of said display, and
control signal generating circuitry in the display controller for
producing a control signal when the cursor reaches predetermined
locations on the screen, and
wherein the surface over which the mouse is to move is non-specific
and the means for sensing motion of the mouse includes a spherical
ball contacting said surface and being rotatable when said mouse is
moved and two pickup wheels in frictional contact with said ball at
a location remote from said surface for detecting motion of the
ball along the X and Y axes thereof, the electromagnetic means for
producing resistance to the motion of the mouse comprising
electromagnetic braking elements physically connected to resist
axial movement of the X and Y frictional pickup wheels when
energized, and
brake energization circuitry actuable in response to said control
signal for selectively energizing said electromagnetic braking
elements,
said control signal generating circuitry further including,
means for producing said control signal as a digital "magnetization
function" signal of a magnitude proportional to the desired
resistance to motion of the mouse as it approaches a predetermined
location on the screen,
a digital-to-analog converter (D/A) for producing an analog signal
from said digital magnetization function, and
a magnet driver circuit comprising:
an operational amplifier (op-amp) connected to the output of the
D/A converter,
a power transistor, which supplies energization current to the
magnet under control of the op-amp,
a protection diode connected in parallel with the electro-magnet,
and
a sense resistor in the emitter circuit of the power transistor for
providing control information to said op-amp.
2. A display system as set forth in claim 1, said control signal
generating circuitry including means actuable for analyzing the
display signal contiguous to the current position of the cursor,
and
means for continuously computing a neighborhood magnetization
function for the cursor whose magnitude is proportional to a number
of visible objects on the screen within a predetermined distance
from the cursor, and
means actuable in response to said neighborhood magnetization
function to cause said control signal generating circuitry to
produce said control signal having a magnitude proportional to the
magnitude of said neighborhood magnetization function.
Description
FIELD OF THE INVENTION
The present invention relates generally to the field of cursor
controllable video display systems and more specifically to such
systems wherein the movement of the cursor may be controlled by the
motion of an operator movable input device or mouse due to the
physical interaction of the mouse with a surface over which it is
moved.
BACKGROUND OF THE INVENTION
Video display systems have become almost universal with modern day
computers with the advent of cheaper cathode ray display tubes and
the availability of raster scan displays provided with the
requisite control functions, buffer memories, etc., required for
sophisticated display capabilities. These displays may be used with
either small stand alone computers, or for large central systems
having large numbers of physically distributed workstations. As is
well understood, the video display is a convenient form of system
monitor which may readily be employed for the purpose of
controlling the operation of the computer by an operator having
minimal experience in sophisticated computer operation areas such
as programming. Thus, with menu driven types of systems a display
appears on the screen with a plurality of possible actions or
options from which the operator must choose. This choosing or
selection can, of course, be done by typing alphanumeric inputs
with a keyboard as is well known; however, in recent years
selection by positioning a cursor in the display at the option or
action of choice has been found to be far quicker and easier to use
from an operator's point of view. Thus, the cursor controller
display is becoming increasingly important as a means of
controlling the computer both in the area of text processing and
also in the field of computer aided design and drafting systems
where rapid movement and precise final location of the cursor is
important.
Originally cursors were moved almost exclusively by means of up,
down, right, left keys on a keyboard, but it has been found that a
much more versatile type of cursor movement is possible with the
mouse type of input device.
The mouse, as generally known in the art, utilizes motion over a
surface wherein a sensing means located within the mouse is
utilized to detect motion and, in effect, produce incremental
signals which are applied through a straight forward system
interface to produce motion of the cursor in the X or Y direction
on the display screen. Usually the mouse is shaped to fit
conveniently in the hand of an operator sitting at a console table
and is frequently provided with several function control keys such
as shown in U.S. Pat. No. 4,550,316. The only way that the operator
has of knowing where the cursor is located on the screen is by
actually viewing the cursor as it moves across the screen.
Many different types of mice are available at this point in time.
Each generates the required cursor control signals based primarily
upon motion of the mouse across a surface (usually planar);
however, the particular interaction of the mouse with the surface
has traditionally taken a wide variety of forms. In a first type of
mechanical pickup mouse, the mouse comprises a housing supported
for rolling motion upon two wheels or sets of wheels which are
disposed at right angles to each other. Thus, as the mouse is moved
across the surface the respective wheels will either roll or slide
depending upon the direction of the motion of the mouse. The
rotation of the wheels causes X-Y displacement signals to be
produced and sent to the video display system. The signals are
translated into movement of the cursor.
In a second type of mechanical mouse the wheels are replaced by a
single sphere which contacts the surface on which the mouse is to
move and two wheels or sets of wheels are located internally of the
mouse which are in intimate contact with the sphere and translate
the motion of the sphere into two quadrature X-Y signals which are
similarly converted into electrical signals and utilized to control
motion of the cursor on the screen. U.S. Pat. No. 3,892,963 of
Hawley and U.S. Pat. No. 3,835,464 of Rider, respectively, disclose
the two above described systems.
In other types of systems optical means have been utilized to
produce the requisite motion signals as the mouse is moved across
the surface and a light source and sensors, placed in various
locations around the surface, pickup the motion of the mouse. Such
a system is described in U.S. Pat. No. 4,364,035 of Kirch.
However, in all of the above described systems, the only feedback
between the operator and the mouse is the visible feedback on the
display screen wherein the operator watches the position of the
cursor as mouse motion causes it to move across the display screen.
It is believed that there is a need in this technical area for a
mouse having a feedback means wherein a clearly recognizable
indication is fed back to the mouse that is apparent to the
operator when the movement of the mouse has caused the cursor "to
arrive" at some predetermined position or neighborhood on the
screen. Thus, in a menu type of system the feedback would indicate
to the operator that he had correctly positioned the mouse in a
selection square or box on the screen. Alternatively, if some sort
of computer assisted design work were being done a "resistance to
motion" feedback of the mouse would indicate, for example, that the
cursor had reached a particular line or lines on the screen and
that the cursor was precisely oriented with respect thereto. Such a
functional capability would free the operator from having to
continually watch the screen especially where it was necessary for
him to be concurrently viewing something else such as a template on
the planar surface or some other material necessary to the
application at hand. No systems are currently available which
provide for the generation of such resistance-to-motion feedback to
the mouse which may be physically perceived by the user.
The expression "resistive feedback" as used herein means, any
resistance-to-motion feedback signal to the mouse which produces a
user discoverable resistance to the motion of the mouse.
DESCRIPTION OF THE PRIOR ART
No patents are known to applicants disclosing or suggesting a
motion-resistive feedback mouse as taught by the present
invention.
The following two patents are cited, in addition to the three
discussed above as background art, in that they are exemplary of
mouse controlled cursor movement systems in an overall video
display system.
U.S. Pat. No. 4,303,914 of Page disclosed a typical input mouse for
controlling the position of the cursor on an associated display
screen by moving the mouse over a slightly roughened planar
surface. Means are provided to generate electrical pulses of a
particular polarity to effect movement of the cursor on the
screen.
U.S. Pat. No. 4,550,316 of Whetstone et al. discloses a somewhat
similar mouse to the one described above in that transducers detect
quadrature direction signals in response to a stylus being used on
a planar surface.
Both of the above systems relate to a signal input mouse and
neither suggests any resistive feedback means for alerting the
operator that the cursor on the screen is approaching or is at a
predetermined location.
The following two publications both relate to a mouse system having
a braille cell mounted on the mouse which allows a braille pattern
to be raised when the cursor intercepts an alphanumeric character
on the CRT screen. The system includes complicated table look-up
algorithms to access the character stored at the X-Y location of
the cursor and neither discloses nor suggests any mechanism for
providing a resistance to motion of the mouse. "New Role for
`Mice`" by J. Timothy Ohsann, appearing in the Research magazine,
Spring '87, page 22, available from the IBM Corporation, Thomas J.
Watson Research Center, Yorktown Heights, New York 10598. An
article by Liam Comerford entitled "Seeing Eye Mouse", IBM
Technical Disclosure Bulletin, Vol. 28, No. 3, Aug. 1985.
SUMMARY AND OBJECTS OF THE INVENTION
It is a primary object of the present invention to provide a
resistive feedback mouse for use with a cursor controlled video
display system.
It is a further object of the present invention to provide such a
mouse wherein a resistive feedback detectable by an operator is
produced when the cursor whose position is controlled by the mouse
reaches predetermined positions on the display screen.
It is a further object of the present invention to provide such a
mouse wherein the feedback comprises a pronounced resistance to the
motion of the mouse as it is moved across a control surface.
It is yet another object of the present invention to provide such a
mouse wherein the control surface or pad is a magnetic material and
the resistive feedback means comprises a selectively energizable
electro-magnet mounted within the mouse which produces a strong
magnetic field which causes increased resistance to further
movement of the mouse across the surface.
It is another object of the invention to provide suitable control
circuitry actuable by the video controller for producing suitable
electrical "control signals" for energizing the electro-magnetic
mouse.
The objects of the present invention are accomplished in general by
a video display system having a display screen, a computer for
controlling video display operations and a mouse for controlling a
cursor on the display screen by movement of the mouse across a
surface. The mouse of the present invention is unique in having
feedback means, which may be totally separate from the movement
pickup means, and which transmits to an operator a resistance to
movement of the mouse as the cursor controlled thereby approaches
or reaches a predetermined point on the screen.
In a preferred embodiment of the invention the feedback responsive
means comprises an electro-magnet mounted in the mouse adjacent to
a ferro magnetic surface over which the mouse is moved whereby
energization of the electro-magnet produces a strong magnetic field
which is turn produces a force proportional to the intensity of the
magnetic field to be exerted between the mouse support slides and
the ferro magnetic surface thereby increasing friction and
resistance to further motion of the mouse. The energizing circuitry
may be either binary (e.g., on or off) or analog whereby a varying
resistance to motion would be produced to provide an indication to
the operator that the cursor is approaching a predetermined
location on the screen.
It should be clearly understood that the feedback responsive means
utilized in the mouse of the present invention may be completely
separate from an functionally unrelated to the particular means
employed within the mouse for sensing motion of the mouse.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a computer work station comprising
a display, a computer console, and a mouse/pad assembly.
FIG. 2 is a cross-sectional view of a preferred embodiment of an
electro magnetic resistive feedback mouse constructed in accordance
with the teachings of the present invention.
FIG. 3 is a functional schematic diagram of an analog control
circuit for the mouse of FIG. 2.
FIG. 4 is a functional schematic diagram of a binary digital
control circuit for the mouse of FIG. 2.
FIG. 5 is a diagram illustrating an alternative embodiment of a
magnetic braking arrangement for use with a mouse provided with a
spherical ball tracking element, said mouse being suitable for use
on a non-specific surface.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The resistive feedback mouse of the present invention preferably
uses an electro-magnet inside a standard mechanical or optical
mouse to provide the requisite resistance to motion under computer
control. As stated previously, a conventional mouse is a device
used in conjunction with certain video display systems marketed by
IBM and others for providing X-Y coordinate input data to the
display system by moving the mouse over a planar surface. Such mice
are difficult to position precisely with respect to screen objects,
such as a grid, as all points feel the same to the user. Thus, the
positioning requires the operator to carefully watch the cursor on
the screen. According to the present invention, by selectively
energizing the electro-magnet using appropriate software, the
resistive feedback mouse alters the apparent texture of the flat
surface. It will of course be noted that the flat surface must be a
ferro magnetic material in order for the preferred embodiment of
the invention to work. Thus, if the magnet is energized at grid
lines, the user will "feel" the grid as the mouse causes the cursor
to pas over the individual lines whereby the cursor may be more
precisely located on the grid.
In graphic editing applications the mouse could be used to
designate a graphic element on the screen which requires a change,
etc. As will be apparent from the following description of the
present invention, it will be seen that the resistive feedback
mouse described herein provides a powerful and flexible feedback
function at a very low cost.
The resistive feedback mouse can be incorporated into any
mouse-oriented work station environment. An example of this is an
IBM Personal Computer APA (All Points Addressable) display
operating within a mouse-oriented environment such as IBM Top View.
The Microsoft Corporation and Digital Research Inc. make similar
mouse-oriented workstation products.
The preferred embodiment of the present invention comprises a
magnetic version of the resistive feedback mouse and more
particularly one wherein an electro magnet is located within the
body of the mouse and interacts with a ferro magnetic planar
surface over which the mouse moves. Other possible embodiments will
be discussed briefly subsequently. The details of the required
additional hardware for supporting the magnetic version of the
feedback mouse will be set forth in more detail subsequently;
however, it would consist of at least a magnet driver circuit to
energize the electromagnetic circuit, which would typically consist
of an amplifier and finally a driver stage to provide the required
coil current in the magnet.
The amplifier can be either analog or binary (on/off). The binary
amplifier is simpler but only allows the mouse to be fully
energized or de-energized. An analog amplifier control circuit
allows the resistive feedback to have a varying magnitude. This
could produce a ramp effect or gradual increase to resistance to
motion as the cursor approaches some predetermined area of the
screen. The power for the magnet driver circuit could either be
extracted directly from the work station or from an external power
supply provided therefor. The magnet driver circuit would be
interfaced to the workstation through either a single bit of the
interface for the binary implementation or through an analog port
where analog control of the mouse is required.
The mouse control software on the workstation must be adapted to
support the resistive feedback mouse. However, as will be seen from
the following, this control would be very simple and straight
forward. The mouse control software on conventional workstations
currently performs the following services. Whenever the user moves
the mouse, the new X-Y coordinates are computed and made available
to the workstation software. This function is performed
automatically using a combination of hardware and software.
Enhancing the function of the mouse control software with the
resistive feedback mouse would be quite simple. All that is needed
for the workstation software to compute is a "magnetization
function" M(x,y), which for every coordinate pair (x,y) on the
screen indicates to what degree the resistive feedback mouse should
be energized (magnetized). For binary control of the mouse this
will of course be a single bit binary function of "one" or "zero"
for on or off. For an analog embodiment, this would be a
multi-valued function (e.g., 8 bits). The mouse control software
would then be modified as follows: when ever new (x,y) coordinates
are computed, M(x,y) is computed and its value is sent to the
magnet driver to change the level of magnetization as appropriate.
It should be noted that a particular application does not have to
control the magnet driver. This could all be incorporated basically
in the systems support software. The feedback function could either
be set on or off and, in the case of an analog function, a
threshold could easily be set below which mouse feedback circuitry
would be de-energized.
For many applications, the resistive feedback mouse would be used
to provide a feedback relative to graphics on the screen. For such
applications, all that would be required of the mouse control
circuitry would be to energize same when the mouse is pointing at
visible graphics (such as text or grid lines) and to de-energize
the mouse feedback circuitry and when pointing at empty space (such
as between words or text lines). In these cases a very simple
magnetization function called a "neighborhood function" can be
used. The neighborhood function N(x,y) merely looks at the graphics
in a close neighborhood of coordinate (x,y) representing the
current position of the cursor. For example, it examines the 3 by 3
pixel square around (x,y) and computes the ratio of visible
graphics to blank space. By energizing the feedback circuitry to
the mouse whenever this ratio is high, the desired resistive effect
is achieved. The binary version of the control circuitry is
energized if the neighborhood ratio is above a certain threshold,
whereas the analog version could produce an energization in
proportion to the ratio. The chief advantage of using the
neighborhood function as a magnetization function is that it can be
computed automatically with the mouse control software. The user
does not have to provide a magnetization function at all.
Application software which effects to use the neighborhood function
does not have to be modified at all to gain the advantage of the
herein described feedback mouse. The system could be easily
arranged so that the neighborhood function would be the default
feedback function if no other was specified.
Advanced applications which wish to provide more than merely
feedback of visible graphics must specify a magnetization function.
An example of this is where there is an invisible grid which,
although not displayed, could still be felt using the resistive
feedback mouse. Another such application might be a furniture
moving simulator, where the mouse is energized in proportion to the
weight of the furniture to be moved. Since any M(x,y) can be
computed by the application there is no limit to the ways in which
the resistive feedback mouse can be used.
There will now follow a specific description of the herein
disclosed preferred embodiment of the present resistive feedback
mouse.
FIG. 1 is a diagram of a small computer system comprising a
computer 2, a computer display 4, a mouse 6, a pad 8 which provides
a working surface for the mouse, a cable 10 which provides the
electrical connections between the mouse and the magnet-driver
brake energizer circuit module 12. The circuit module is mounted in
the rear of the computer in a slot normally provided for
interfacing a computer to peripheral devices.
FIG. 2 is a side elevation cut away view of the mouse employing
magnetic means to achieve resistive feedback . The magnetic version
of the mouse according to the invention generally comprises the
housing 14 adapted for supported sliding movement on a specific
magnetic pad surface 16 by means of slide pads 18 which are affixed
to the underside of the housing. Mounted within the housing 14 and
physically attached thereto is an electro-magnet 20 positioned with
the bottom pole located in close proximity to the magnetic pad
surface 16 . Cable 10 provides the electrical connection between
electro magnet 20 and the magnet driver circuit located in the
magnet driver brake energizer circuit module 12 which is mounted
within the computer 2. As with conventional mice, there is
contained within the mouse housing 14 a tracking mechanism 22
which, in cooperation with hardware and software located elsewhere
within computer 2, provides for conventional operator control of
the movement and positioning of the cursor on the computer display
4.
The mouse, according to the invention, provides for resistive
feedback to the operator of the mouse under computer control. With
reference to FIG. 2, resistive feedback is achieved by controlling
the degree of sliding friction between the slide pads 18 and the
magnetic pad surface 16. Sliding frictional forces arise at the
points of contact between the tips of the slide pads 18 and
magnetic pad surface 16 whenever the mouse is in motion across
magnetic pad surface 16. These forces occur in the plane of
magnetic pad surface 16 and are oriented in a direction opposite
that of the direction of movement of side pads 18 across magnetic
pad surface 16. Thus, the frictional forces arising during movement
of the mouse across the magnetic pad surface occur in an
orientation so as to directly oppose further movement. The
magnitude of the sliding frictional force at a given slide pad is
dependent upon the product of the co-efficient of sliding friction
and the magnitude of the downward force at the slide pad normal to
magnetic pad surface 16. Thus, by varying the degree of
magnetization of electro magnet 20, the magnitude of the downward
normal forces at the slide pads 18 may be varied, thereby varying
the magnitude of the sliding frictional forces occurring between
slide pads 18 and magnetic pad surface 16, which in turn varies the
degree of resistance to further sliding of the mouse housing 14
across magnetic surface 16 experienced by the operator. The degree
of magnetization of electro magnet 20 is controlled by the
magnitude of the electric current supplied thereto via cable 10 by
the magnet driver circuit.
A magnetic resistive feedback mouse according to the invention may
be operated in a linear (proportional) or a nonlinear (on/off)
mode, said mode being determined by the nature of the magnetization
current supplied to electro magnet 20. In the linear mode, the
magnet driver circuit would be capable of supplying a continuously
variable current under computer control. Operation in the nonlinear
or binary (on/off) mode would require that the magnet driver
circuit be capable of supplying a fixed magnitude current which may
be turned on or off under computer control.
FIG. 3 is a diagram of a magnet driver circuit suitable for
operating a magnetic feedback resistive mouse in the linear or
proportional mode. The circuit comprises a power transistor 24, an
operational amplifier 26, a digital-to-analog converter 28, a sense
resistor 30, and protection diode 32. At the left of the diagram
the digital-to-analog converter 28 receives a digital input code
from the Central Processing Unit or CPU which is part of computer
2, and produces a proportional analog voltage at its output which
is then supplied to the positive input of operational amplifier 26.
Operational amplifier 26, in conjunction with power transistor 24
and sense resistor 30, form a closed loop voltage-to-current
converter circuit. The degree of conduction of power transistor 24
is controlled by operational amplifier 26 which compares the
magnitude of the voltage drop across sense resistor 30 with the
analog voltage received from digital-to analog converter 28. Thus,
the current from the positive voltage source. V+, through cable 10
to electro magnet 20, through power transistor 24 and sense
resistor 30 to ground, is made to correspond in magnitude to the
digital input code from the CPU. The instantaneous degree of
resistance experienced by the operator of the magnetic resistive
feedback mouse to motion along magnetic pad surface 16 is
controlled in this manner by the digital input code supplied from
the CPU residing within computer 2. Protection diode 32 protects
power transistor 24 against exposure to excessive back-emf that
would occur if electro magnet 20 were rapidly de-energized.
FIG. 4 comprises a diagram of a magnetic driver circuit suitable
for operating the magnetic resistive feedback mouse in the
nonlinear or on/off mode. Power transistor 34 functions as an
on/off switch under control of binary amplifier 36 which in turn
receives an input from the Central Processing Unit residing in
computer 2. When a binary input from the CPU is received
corresponding to the off condition, binary amplifier 36 applies a
voltage to power transistor 34 which places it in the nonconducting
state. Consequently no current is supplied to electro magnet 20.
When a signal is received from the CPU corresponding to the "on"
condition, binary amplifier 36 applies a voltage to power
transistor 34 placing it in the fully conducting state. A current
is established from the positive supply, V+ through current
limiting resistor 38, through cable 10 to electro magnet 20, and
through power transistor 34 to ground. Current limiting resistor 38
is included to establish the magnitude of the on-state current, and
protection diode 40 serves to protect power transistor 34 against
potentially destructive voltage transients as described
previously.
FIG. 5 is a functional block diagram of an alternative embodiment
of the resistive feedback mouse of the present invention. In this
embodiment, electro magnetic brakes 50 and 52, totally
self-contained within the mouse, enable a controlled braking effect
to be applied directly to the spherical tracking element 58,
thereby producing resistance-to-motion feedback. Thus, the
embodiment of FIG. 5 eliminates the need for a ferromagnetic work
surface, and may be utilized with a mouse which is adapted to be
movable on any non-specific surface.
The embodiment of FIG. 5 could utilize a mouse having a spherical
ball pickup such as disclosed in U.S. Pat. No. 3,835,464 of Rider.
In this embodiment the x-axis electro magnetic brake 50 and the
y-axis electro magnetic brake 52 are shown mechanically attached to
the x-axis motion pickup wheel 54 and the y-axis motion pickup
wheel 56, respectively. The two pickup wheels are in turn located
with respect to the spherical tracking element 58 to detect
quadrature rotations of the spherical tracking element. As stated
previously the basic pickup system utilizing an x-axis motion
encoder 60 and y-axis encoder 62 are essentially unaffected by the
details of the present invention. It would of course be necessary
for the shaft extension 64 and 66 to be provided for the purposes
of mounting simple electro magnetic brakes 50 and 52. As will be
apparent, a braking signal applied to either or both of the
magnetic brakes would cause a resistance to motion of the mouse in
either or both the X and Y directions. The circuitry for generating
the braking pulses could be identical to those described
previously, e.g., the analog magnet driver circuit of FIG. 3 could
be utilized or the binary magnetic driver circuit of FIG. 4 could
be used. Similarly, the X and Y brakes could be driven in parallel
utilizing the software functions described previously, or they
could be driven separately by separate driver circuits utilizing
magnetization functions which considered only the X or Y
coordinates for deriving the braking function.
In addition to the embodiment of FIG. 5 it will be course be
obvious that the braking concept of FIG. 5 could easily be adapted
to a two wheel mouse such as described previously wherein the X and
Y motion pickup wheels directly contact the surface as opposed to
being driven by the motion of the spherical tracking element as in
FIG. 5.
Other possible embodiments of the present invention to produce
resistive, operator-discernible feedback might include an on-off
solenoid having a vertically-disposed movable element which would,
in effect, act as a mechanical brake when energized.
The position detection and resistive feedback signal generating
circuitry for producing resistance to motion would be essentially
the same as for the previously described embodiments as will be
well understood by those skilled in the art.
Other modifications and changes could be readily made by those
skilled in the art without departing from the spirit and scope of
the present invention as set forth in the appended claims.
* * * * *